Animation gets cut off early and sprites don't show on animation tab

Hey all. Couple questions that I don't understand nor can I find an answer for.

I made a new animation and I noticed that the timeline ends immediately after the last animation frame I put in, so the last frame gets played for a fraction of the time as opposed to the other frames. This ends up giving the animation a bit of a stutter at the end before it repeats. I managed to fix it by repeating the last frame again, but what's odd is that some of my other animations don't do this. The last frame gets played for the same amount of time as the others.
For example, here's the timeline for a walk cycle I have. Notice how there's some space between the last frame and the end.


Doing the same thing for my run cycle except it kept getting cut off early (the last two frames are the same ones).


It's not too big of an issue, but it is kind of annoying. Why does it sometimes do this and how do you fix it?

The other question I have is how do you get the sprites to appear on the timeline? I've seen a bunch of images and tutorials where the bottom diamond icon is actually the exact sprite that you put in, but mine never shows up like that. How do I get it to show the sprites?